The design of passenger seats for aircraft requires consideration of passenger comfort, the number of seats and space limitations in a particular aircraft, and the location of the seat in the aircraft. Passenger seats generally include an aluminum base frame assembly to which are attached reclining seat backs, center arm rest assemblies, fold-down food table assemblies, and fully upholstered seat back and bottom cushion assemblies.
In the past, the bottom cushion assembly of the individual passenger seat was supported by a conventional bottom diaphragm formed of an aluminum sheet that was riveted along its edges to the tops of the stretcher tubes between two of the spreaders. The riveted aluminum sheets were difficult and time consuming to remove and replace. Other bottom diaphragms have been constructed of fabric or webbing which tends to wear out and fray.
U.S. Pat. No. 4,277,103 discloses a continuous sheet of aluminum shaped to establish a natural seat bottom depression to prevent pelvic rotation.
U.S. Pat. No. 4,630,864 issued Dec. 23, 1986 to Ian C. Toll discloses a seat diaphragm stiffened with a panel of structural foam and skinned with carbon fiber material.
Seat cushions for aircraft seats are generally made of soft, open-cell, low density comfort foam, such as polyurethane. If floatation assistance is not required, the cushion may be constructed entirely of this type of open-cell foam.
If a bottom seat cushion is to provide a passenger with floatation assistance for emergency ditching, a portion of the comfort foam is generally replaced with a hard, closed-cell higher density floatation foam. Heretofore, replacing the comfort foam with floatation foam, made the cushions harder and less comfortable. Thus, it has often been the goal, when designing bottom cushions, to use only enough floatation foam to meet regulatory requirements. This has usually meant that the cushion contained multiple small pieces of floatation foam, placed around the underside of the cushion, in an effort to maximize the comfort foam.
Often seat design becomes a compromise of comfort versus floatation versus safety when placing the floatation foam in the cushion. The floatation foam has the ability to dissipate energy better than comfort foam when placed in the cushion to reduce the spinal impact energy that a passenger receives during a crash.
Business class and first class seats can be provided with a console with personal storage compartments, compartments for cocktail trays, and the like. A first class sleeper seat may include additional features such as a video monitor, an extendable leg rest, and other features for passenger comfort and convenience.
Economy or coach passenger seats are generally narrower and more densely spaced than business class or first class seats. Further, the seats of commuter aircraft are generally closer spaced and more dense than seats for larger wide-body international flights.
The spacing of spreaders and legs along the length of the stretcher tubes will vary for different types of seats and different seating arrangements. The position of legs on seats nearest the aisle and seats nearest the wall of the aircraft may vary depending upon the structural design of the aircraft, the number of seats in the row and the location of the row of seats in the aircraft. The connections between spreaders and stretcher tubes and between leg assemblies and stretcher tubes often vary depending upon the location of the spreaders on the stretcher tubes, the location of the legs on the stretcher tubes, and whether the seat is a front facing seat or a rear facing seat.
Heretofore, the construction and maintenance of aircraft seats has been very expensive because operations have been labor intensive. Furthermore, the size and shape of components of the seat vary depending upon the location of the installation in the aircraft, resulting in a multitude of parts that must be kept in inventory for proper maintenance. Periodic maintenance required on aircraft seats generally requires replacement or disassembly of the entire seat merely for replacing or installing a component in the seat assembly.
The important structural requirements for safety must be met and at the same time the airline operator needs to be able to easily and cost effectively maintain the seats. It is often necessary to change the seating configuration in the aircraft to meet different passenger and market needs. In the past, the assembly and disassembly of the seats has been a complicated, time consuming, and expensive process, often requiring that most of the seat support structure be disassembled in order to move or change the seating configuration. Furthermore, every reduction in the weight of the seats without reducing the structural integrity saves the airline fuel and reduces operating expenses.